It is proposed to hold a scientific meeting in Saranac Lake, NY, from July 27-30 to honor the centennial of the Trudeau Institute. In keeping with the research mission of the Institute, the meeting will deal with the state of our understanding of the immune response to infecious agents, tumors and allografts. The meeting will consist of presentations from 30-40 key speakers who have been chosen on the basis of their scientific prowess, reputation, maturity and wisdom, and because they currently are active in their fields of expertise. About 60 additional researchers will be encouraged to register and attend the meeting for the purpose of participating in formal and informal discussion and in poster sessions. A major purpose of the meeting is to provide for interactions among established researchers engaged in studying immunology at the physiological, cellular and molecular levels. Topics to be covered include the anatomy of the lymphoid and mononuclear phagocyte systems, and the physiological properties of the cellular components of these systems during conditions of steady state and responsiveness to colonization by replicating antigen types. The immune response will be dealt with at the cellular level in terms of the cells types and cellular interactions involved in the induction, generation and expression of an immune response. The function of key lymphokines in these interactions will represent the molecular aspect of the meeting. The meeting will result in a publication that will deal with our current knowledge of immunity to infections, tumors and allografts. The publication, like the meeting itself, will stress the need to interpret the results of in vitro analysis in terms of the in vivo function. It also will stress the value of analyzing the immune response at the physiological level in the whole animal.